Problem: What do the following two equations represent? $5x-y = 3$ $-15x+3y = -9$
Explanation: Putting the first equation in $y = mx + b$ form gives: $5x-y = 3$ $-y = -5x+3$ $y = 5x - 3$ Putting the second equation in $y = mx + b$ form gives: $-15x+3y = -9$ $3y = 15x-9$ $y = 5x - 3$ The above equations turn into the same equation, so they represent equal lines.